Floor spectra validation through actual data from the 2016/2017 earthquake in Central Italy

Analytical expressions as much as possible reliable to assess the possible amplification phenomena due to the filtering effect of the main structure play a key role for a correct definition of the seismic input induced on non-structural elements in existing buildings. Traditionally, the approach adopted by Codes refers to the definition of the seismic action in terms of floor spectra, which are based on the simplified assumption to neglect the dynamic interactions between primary and secondary structures. Due to the complexity of such amplification phenomenona, furthermore possibly raised by the nonlinearity of the building itself, accurate data on existing structures hit by real seismic events constitute a precious source for a better understanding of the topic and for corroborating the validation of analytical expressions. In this framework, the paper aim is twofold. On one hand, it attempts to interpret the physics of the amplification phenomenon through some experimental evidences coming from both laboratory tests and in-situ measurements on existing structures monitored by the Italian structural seismic monitoring network (OSS). On the other hand, it presents the application of an analytical expression for the floor spectra developed by the Authors to a casestudy consisting in the Pizzoli’s town hall, hit by the 2016/2017 earthquake in Central Italy and permanently monitored by OSS since 2009. With the aim of validating the expression both in the linear and nonlinear fields, the comparison between experimental and analytical floor spectra has been provided for both a minor seismic event and the main event of 18/01/2017, after which the structure exhibited a moderate damage level. Even if the research is still ongoing, the first results appear promising.